David Ashworth builds systems for a living. He does not hear voices. A data scientist and quiet Christian living in rural Sussex, David has spent seven years building a life that makes sense — a wife who grounds him, two children who need him, a mind that finds patterns in everything. The blackouts are nothing. The handwriting on Post-it notes he doesn't remember writing is nothing. The moments where his wife says "you were someone else" are nothing he can't explain away. Then he visits Chartres Cathedral, and a woman who died seven hundred years ago opens her eyes inside his head. She recognises the carvings. Not as art. As a message she helped encode. As David's world fractures, more voices surface — a biblical scribe, a Templar knight, a Victorian seamstress — each carrying a fragment of knowledge about the most dangerous object in human history. Each placed inside him by a bloodline that stretches back 2,600 years. His therapist wants to help him. She is the most dangerous person in his life. Seven years. Seven alters. Seven voices. One of them is lying.